Vapor barriers are not as critical as once thought. The critical issues are air tight and maintaining low humidity on the inside of the house. +40%RH during extreme cold weather puts vapor pressure on the insulation in the walls and attic insulation. The greatest vapor barrier in the exterior insulation system should be on the predominately warm side of the insulation. Areas like bath rooms with showers are critical for the vapor barrier location. Season Greetings Regards TB
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"